5W30 vs 10W30: Which Oil Is Better for Your Engine?

5W30 vs 10W30 oil — what’s the right choice for your engine?

While both are multigrade oil types suitable for a colder climate, they differ in terms of low temperature viscosity and vehicle compatibility.

Read on to explore the major differences between the two oils and examine their characteristics to determine the better choice for your engine.

5W30 vs 10W30: What Are They?

5W30 and 10W30 are multigrade oil types available as conventional oil and synthetic oil variants. They help reduce friction between moving engine parts and extend engine life.

Now, engine oils are classified by a rating system developed by the Society of Automotive Engineers (SAE). This rating system categorizes oil based on its viscosity, i.e., its resistance to flow. Motor oil viscosity changes at different temperatures, becoming thinner at hot temperatures and thicker in cold climates.

Multigrade viscosity motor oils, like 5W30 and 10W30, are designed to perform across different temperatures. That’s because they contain viscosity improvers and two oil viscosity grades:

Cold temperature viscosity grade: Indicated by the number before the letter ‘W,’ it refers to the oil’s viscosity at a low temperature.
High temperature viscosity grade: Represented by the second number after ‘W,’ it indicates the oil’s thickness at normal engine operating temperature (167°F to 221°F).

The letter ‘W’ stands for ‘Winter,’ indicating that both oils are suitable for cold weather conditions.

NOTE: Viscosity improvers allow a multigrade oil to resist thinning or thickening under extreme temperature conditions. However, a single viscosity grade motor oil (like SAE 30) doesn’t use viscosity index improvers. It has a fixed viscosity index, meaning it doesn’t adapt to temperature changes. These oils are formulated to perform at either hot or cold temperatures but not effectively across a broad range.

With that said, let’s see how 5W30 and 10W30 hold up against each other.

5W30 vs 10W30: What’s the Difference?

Even though both the oils are multigrade engine oil types, they differ in aspects like:

1. Low Temperature Viscosity

To understand the oil’s viscosity rating at lower temperatures below 32°F, look at the first number before W in the SAE oil grade. This number is important for your engine’s startup in cold climates.

A lower viscosity number means thinner oil, which circulates faster during cold starts. When you compare both oils, 5W30 engine oil has a lower viscosity rating (“5”) in freezing temperatures, implying the oil thins fairly in lower temperatures. This makes it a better winter engine oil than 10W30.

On the other hand, 10W30 oil has a higher number before ‘W,’ meaning it won’t flow as quickly as 5W30 oil at lower temperatures (below 32°F).

However, both engine oils are SAE-graded for cold weather performance and possess low-temperature viscosities. This implies that both multigrade oil types perform relatively well in cold temperatures compared to other oils.

2. High Temperature Viscosity

The second number after the ‘W’ denotes the oil viscosity at a high temperature or the engine’s operating temperature. The higher the second number, the thicker the oil remains at the engine’s normal operating temperature.

Since 5W30 and 10W30 have the viscosity of an SAE 30 single-grade oil, they can resist becoming a thinner oil at higher temperatures.

That said, their high-temperature performance won’t equal that of a higher-viscosity oil like 10W40.

3. Temperature Performance Range

Since 5W30 and 10W30 are multigrade oil types, they perform well across a broad temperature range.

5W30 engine oil functions effectively between -22°F to 95°F, whereas 10W30 oil operates within a slightly narrower range of -13°F to 86°F.

4. Suitable Vehicle Types

5W30 oil is ideal for private vehicles and light-duty petrol and diesel engines, such as those in Honda, Toyota, and more.

On the other hand, 10W30 — a slightly thicker oil — provides better lubrication for commercial vehicles and heavy-load engine cars. Although this multigrade engine oil can be used for colder temperature environments, it’s also suitable for slightly warmer climates.

Now that we have compared both oils, it leads us to an important question:

Should You Go for 5W30 or 10W30?

Both 10W30 and 5W30 oil are good options for cold weather performance. However, the right choice of oil depends on your vehicle’s requirements, location, and the prevailing climate.

If you live in freezing conditions with temperatures below -13°F, you should go for 5W30.

NOTE: Synthetic oil formulations of 5W30 and 10W30 will hold up better in a colder climate than their conventional oil counterparts, thanks to their reengineered molecular structure.

Got more questions about these multigrade oils?
Keep reading.

4 FAQs About 5W30 vs 10W30

Check out these commonly asked questions related to multigrade engine oil types:

1. Can You Mix 10W30 and 5W30?

No, you shouldn’t mix oils of different viscosity ratings. Doing so can alter the engine oil’s ability to maintain its structure across different temperatures, leading to ineffective lubrication.

Additionally, different oils contain different viscosity modifiers and corrosion inhibitors that may be incompatible with each other.

It’s always best to stick to the viscosity oil requirements mentioned in the engine manual.

2. Should You Use a Thicker Oil for High-Mileage Cars?

Yes, but instead of merely choosing a thicker, higher-viscosity oil, it’s better to use a high-mileage oil designed for aging vehicles.

While thicker oil can help increase oil pressure in an older engine, it may not be necessary for modern engines manufactured in the last decade.

With advancements in oil chemistry, oil filters, and engine design featuring tighter tolerances, friction-related wear has significantly reduced, and oil passages are no longer as wide as they used to be. So, a higher viscosity oil may not effectively improve oil pressure, but a high-mileage oil can provide the necessary engine protection for aging cars.

3. Can You Use 10W30 Instead of 5W30 Motor Oil?

Yes, but only if it’s a recommended viscosity oil for your engine.

Otherwise, it’s always best to use the manufacturer-recommended viscosity oil for better lubrication and protection against engine wear.

Here’s why:

Using a higher viscosity oil than recommended may lead to increased resistance in cold temperatures, higher oil pressure, and potential overheating. This is because thicker oil doesn’t dissipate heat as efficiently.

On the other hand, a lower viscosity oil (like 5W oil) than what your engine needs will make the oil flow faster, especially in cold starts. If the oil is too thin, it may fail to maintain a consistent lubricating film, leading to metal-to-metal contact between internal engine parts. This contact can result in increased engine wear due to friction.

And that’s not all!

The right motor oil not only protects your engine components but also provides maximum fuel economy and efficient oil consumption, saving you money in the long run.

4. How Do You Choose the Right Oil for Your Vehicle?

Using the right motor oil is key to optimal engine performance. Here are some aspects to consider to help you make the best decision:

Manufacturer’s recommendation: Go for the oil viscosity specified in your owner’s manual. Manufacturers design engines to work best with certain oil types to maximize engine performance and protection.

Climate: If your manual provides a range of options (e.g., 5W20 or 5W30), choose based on your local climate. For colder regions, opt for thinner oils like 5W20, which flow better at a low temperature and help with faster cold starts. For warmer climates, choose 5W30 or 10W30 oil, as they provide better protection at higher temperatures.

API ratings: The oil brand you choose should have the API/ILSAC “Starburst” symbol on the front label and the API “Donut” symbol on the back label. The Starburst logo signifies that the oil meets ILSAC (International Lubricant Specification Advisory Committee) standards for gasoline engines. The Donut symbol indicates the oil’s API (American Petroleum Institute) service rating, SAE viscosity, and resource-conserving properties. These symbols ensure that the oil meets high standards of engine performance. Mobil 1, Castrol, and Valvoline are some brands with these certifications.

Driving conditions: For traffic-prone city driving, a thinner oil like 5W20 may provide slight fuel efficiency benefits. If your car often goes through towing, heavy loads, or off-road driving, a thicker oil like 5W30 or 10W30 offers better protection at the engine’s normal operating temperature.

Vehicle type: Modern engines with tighter tolerances, especially in smaller vehicles, generally benefit from thinner oils like 5W20 for improved fuel efficiency. In contrast, trucks, SUVs, and vehicles operating under heavy load may require 10W30 or 5W30 oil for added durability and engine protection in demanding conditions.

Choose the Right Oil for Performance, Protection, and Peace of Mind

Both 5W30 and 10W30 are good multigrade oil options if you live in a cold climate. However, you need to check your owner’s manual for engine oil specifications.

No matter which oil you choose, regular oil changes are essential to keep your engine running smoothly and prevent damage.

If you’re due for an oil change, let the experts at AutoNation Mobile Service take care of it from your driveway.

Our mobile mechanics will come to you, change the oil, and perform other necessary auto repairs to get you back on the road quickly. We’re available seven days a week and offer upfront pricing, ensuring no surprises.